Tube arrangement for heat exchangers



Oct. 13, 1953 w GAYLQRD, JR 2,655,350

TUBE ARRANGEMENT FOR HEAT EXCHANGERS Filed Sept. 28, 1950 l5 EA Mad. 90R Z 1 2 o J H l5 u v A B RMRJ INVENTOR WILLIAM M. GAYLORELJR.

ATTORNEY Patented Oct. 13, 1953 TUBE ARRANGEMENT FOR HEAT EXCHANGERSWilliam M. Gaylord, J r., Cleveland, Ohio, assignor to Union Carbide andCarbon Corporation, a

corporation of New York Application September 28, 1950, Serial No.187,209

8 Claims.

This invention relates to heat exchangers, and more particularly to ashell and tube type having a stainless steel shell and imperviousgraphite tubes which are chemically resistant to practically allcorrosive fluids, resistant to severe thermal shock, and have high heattransfer rates.

The shell and the tubes therein are cylindrical and have parallel axes.When speaking of shell and tube interchangers, in all cases pitch isdefined as the geometric relation, arrangement or location of the tubes.Square pitch is defined as the arrangement of the tubes with theircenters at the corners of squares. Triangular pitch is defined as thearrangement of the tubes with their centers at the apices of equilateraltriangles. Ligament is defined as the distance between the outsideperipheries of the tubes measured along a lone joining their centers.The conventional arrangement of the tubes is either on a regularequilateral triangular, or on a square pitch. These arrangements requirea relatively large shell to enclose a given number of tubes for a givenligament or spacing between the outside diameter of the tubes.

The main object of the present invention is to provide an advantageousspecific arrangement of tubes which will permit the use of a smaller,but not necessarily minimum, size of shell for a given number of tubesand a given ligament.

According to the present invention the tubes are partly on a squarepitch and partly on a triangular pitch, preferably half and half. Thesetubes are also preferably arranged in rings in concentric relation,those of the inner ring being on a square pitch, those of anintermediate ring arranged in equally spaced pairs equally spaced apartin their ring, the chords connecting said pairs forming the bases ofequilateral triangles, the apices of said triangles being for-med bytubes in another of said concentric rings, and those of the outer ringbeing arranged in pairs equally spaced apart and alternating withsingles which form the apices of triangles having their bases in theintermediate ring. The intermediate ring has double, and the outer ringtriple, the number of tubes of the inner ring. The tubes are arrangedsymmetrically in quadrants, in each of which quardants a tube center ofthe inner ring forms with the two tube centers of the intermediate ringthe apices of an equilateral triangle. and the tube centers of the outerring subtend right angles having vertices at the tube centers of theintermediate ring, and the two farthest apart tube centers in the outerring in the quadrant subtend a right angle having its vertex at the saidtube center of the inner ring.

In the drawings:

Fig. 1 is a vertical cross section through a heat exchanger having tubesarranged according to the present invention; and

Fig. 2 is an enlarged diagram of one quadrant A--A of Fig. 1 showing thegeometrical arrangement and angular disposition of the tubes.

The heat exchanger comprises a stainless steel shell S which enclosesthe group of impervious graphite tubes indicated generally at T. Theshell s has headers H at each end having apertures receiving therespective tubes, so that the headers and tubes contain one of thefluids to be treated. The headers are secured to each other by staybolts or tie rods R. The other fluid is contained in the space insidethe shell and outside of the tubes, which communicates through aperturesE with a manifold M having an inlet or outlet connection C.

The grouping of the tubes T is best shown in Fig. 2. The tubes l0, l4and it have their axes located at the apices of an equilateral triangle.The tubes l4, I5 and [6 are located at the apices of another equilateraltriangle. Thus the four tubes H], l4, l5 and is are all on a triangularpitch. The tubes Ill and I2 have their axes in a line parallel to avertical diameter, and the tubes In and I1 have their axes in a lineparallel to a horizontal diameter. Also the grouping is symmetricalabout both diameters. Hence the tubes I0, i2 and I! are on a squarepitch.

With respect to the line determined by the tubes l0 and I2, the tubes Mare located at an angle of 15 to this line. Thus the tubes In and. I2form a row, in which each tube is at an angle of 15 from an adjacenttube I 4 farther from the diameter.

It will be noted that the four tubes it! determine an inner ring G, theeight tubes M and I5 determine an intermediate ring J, and the twelvetubes l2, l5 and I! determine an outer ring K. Thus the intermediatering has double, and the outer ring triple, the number of tubes withinthe inner ring. The tubes It] of the inner ring are on a square pitch,and the tubes Hi and it of the intermediate ring are on a triangularpitch. As to the outer ring, the tubes Ii! of adjacent quadrants form apair, and the tubes H of adjacent quadrants form another pair, bothpairs being on a square pitch. In this outer ring, the pairs I2, l2 andl1, I! on a square pitch alternate with singles l5 on a triangularpitch.

In the inner ring, the tubes It! are 90 apart. In the intermediate ring,the tubes [4 and I6 are apart, in the sense that the arc of the ring Jbetween the centers of these tubes i4 and I5 subtends an angle of 60having its vertex at the center of tube Ill. Similarly the centers ofthe tubes l4 and I6 determine an angle of 60 having its vertex at thecenter of tube l5. In the outer ring, the tubes l2 and are 90 apart, asare the tubes I5 and IT, in the sense that the arc of ring K between thecenters of tubes I2 and I5 subtends an angle of 90 having its vertex atthe center of tube I4, and the arc of ring K between the centers oftubes [5 and l! subtends an angle of 90having its vertex at the centerof tube Hi.

In the specific embodiment shown for example, there are twenty-fourimpervious graphite tubes all of one and one-quarter inch outsidediameter, and seven eights of an inch inside diameter. The ligaments orspacing between tubes is three eights of an inch from one outside tubeperiphery to the next measured along a line joining their centers. Theinside radius B of the shell is five inches, while all of the tubes liewithin a circle of a radius D of 4.66 inches. This tube circle radius Dfor a rectangular pitch would be 4.875 inches, while for a triangularpitch it would be 4.687 inches.

I claim:

1. Ina heat exchanger, a shell and tubes arranged within said shell inaxially parallel rel-ation and in spaced relation to each other and tothe shell, said tubes being arranged with their centers in rings inconcentric relation, the tube centers of one of said rings beingarranged in equally spaced pairs equally spaced apart in their ring andthe hypothetical chords between the tube centers of said pairs formingthe bases of equilateral triangles, the apices of said triangles beingformed by tube centers in another of said concentric rings.

2. In a heat exchanger, a shell and tubes arranged within said shell inaxially parallel relation and in spaced relation to each other and tothe shell, the centers of said tubes being arranged in rings inconcentric relation, the tube centers of a smaller of said rings formingthe apices of respective equilateral triangles, and the tube centers ofa larger of said rings being ar- I ranged in equally spaced pairsequally spaced apart and the hypothetical chords between the tubecenters of said pairs forming the bases of said triangles.

3. In a heat exchanger, a shell and tubes arranged with-in the shell inaxially parallel relation and in spaced relation to each other and tothe shell, the centers of said tubes being arranged in rings inconcentric relation, the tube centers of an intermediate ring beingarranged in equally spaced pairs equally spaced apart in their ring, thehypothetical chords between the tube centers of said pairs forming thebases of respective equilateral triangles, the apices of which trianglesare at the centers of single tubes which alternate with equally spacedpairs of tube centers in an outer ring.

4. In a heat exchanger, a shell and tubes arranged within said shell inaxially parallel relation and in spaced relation to each other and tothe shell, the centers of said tubes being arranged in rings inconcentric relation, the tube centers of the intermediate ring beingarranged in equally spaced pairs equally spaced apart in their ring andthe hypothetical chord between the tube centers of said pairs formingthe bases of equilateral triangles, certain of said triangles beingwithin said "intermediate ring and having their apices at centers of thetubes of the inner ring, others of said triangles extending outside atthe centers of tubes the outer ring.

5. In a heat exchanger, a shell and tubes arranged within the shell inaxially parallel relation and in spaced relation to each other and tothe shell, the centers of said tubes being arranged in rings inconcentric relation and in symmetrical quadrants, in each of whichquadrants a central tube center in the outer ring forms with the tubecenters on each side thereof equally spaced adjacent pairs which subtendright angles having their vertices'at respective tube centers in theintermediate ring, and said tube centers on each side thereof in saidouter ring subtend a right angle having its vertex at a tube center inthe inner ring in said quadrant.

6. In a heat exchanger, a shell and tubes arranged within the shell inaxially parallel relation and in spaced relation to each other and tothe shell, the centers of said tubes being arranged in rings inconcentric relation, the tube centers of an intermediate ring beingarranged in equally spaced pairs equally spaced apart in their ring andthe hypothetical chord between the tube centers of said pairs formingbases of respective equilateral triangles the apices of which are formedby tube centers in the outer ring which together with the tube centerson each side there:

of in their ring form adjacent equally spaced pairs which each subtend aright angle having its vertex at a tube center of said intermediatering.

7. In a heat exchanger, a shell and tubes arranged within the shell inaxially parallel relation and in spaced relation to each other and tothe shell, the centers of said tubes being arranged in rings inconcentric relation and in symmetrical quadrants, in each of whichquadrants a tube center or the inner ring forms with two tube centers ofthe intermediate ring the apices of an equilateral triangle, and thetube centers of the outer ring subtend right angles having vertices atthe tube centers of the intermediate ring, and the two farthest aparttube centers in the outer ring in the quadrant subtend a right anglehaving its vertex at the said tube center of the inner ring.

8. In a heat exchanger, a shell and tubes arranged within the shell inaxially parallel relation and in spaced relation to each other and tothe shell, the centers of said tubes being arranged in rings inconcentric relation and in symmetrical quadrants, in each of whichquadrants the hypothetical chord between a pair of tube centers of theintermediate ring form the common base for two equilateral triangles,one of which lies Within said intermediate ring and has its apex at thetube center of the inner ring within its quadrant and the other of.which triangles extends outside of said intermediate ring and has itsapex at a tube center in said outer ring, said outer ring tube centerand the tube centers on each side References Cited in the file of thispatent UNITED STATES PATENTS Number Name Date 456,923 Barnstead July 28,1891 1,891,278 Guimont Dec. 20, 1932 2,239,685 Noack Apr. 29, 19412,496,301 Meixl :Feb. 7, 1950

